Error: A. "to" Correct sentence: It is not worth helping her because she is unkind. Explanation: The expression "it is not worth" is followed by a gerund, not an infinitive.

Error: B. "didn’t" Correct sentence: I wish my brother hadn’t taken part in this club 3 years ago. Explanation: "I wish" refers to a past unreal situation, so we use the past perfect ("hadn't taken") instead of the past simple ("didn't take").

Error: C. "a" Correct sentence: Is Huong Pagoda one of the famous religious spots in Hanoi? Explanation: "One of" is followed by "the" (not "a") when referring to a specific group, and "religion" should be in the adjective form "religious."

Error: D. "ate" Correct sentence: They suggest that we should drink more water and eat more vegetables. Explanation: After "should," the verb should be in its base form, so "ate" should be "eat."

Error: A. "lived" Correct sentence: My grandparents used to live in the Central Highlands before they came to this city. Explanation: After "used to," the verb should be in its base form, so "lived" should be "live."